Hydrothermal and solvothermal reactions have drawn attention as means for synthesizing compounds. For example, JP Patent Publication (kokai) No. 2005-36214 A discloses a method for preparing zinc sulfide particles having multiply twinned structures and an average particle diameter of 5 nm to 20 μm via a hydrothermal reaction of a sulfur ion and a zinc ion using water as a reaction solvent at 150° C. to 370° C. during the process of particle growth.
Various chalcogenide compounds have drawn attention as alternatives to existing expensive platinum catalysts.